Underwater sealant

[rjp]

I have recently removed a couple of seacocks from Alysia's iroko hull. After 30/40 years the sealant used was still nice and soft, sticky, watertight etc, but I've no idea what it was. Light brown in colour, with a hint of tranlucency, a bit stringy like toffee when drawn out. All the modern sealants seem to set to a rubbery consistency which is all but impossible to remove and makes it difficult ever to remove the fitting again. Any ideas what might have been used originally, or any recommendations what to use when I replace said fittings?

John

 

[tcm]

if things fit properly there is often no need for actual sealant - rubber washers for the ffange faces, ptfe tape for the thread should make it nice and watertight, no?

 

[Gordonmc]

Sounds like Sealastick.
Orrible stuff to work with... it came in a sausage and had to be trowelled on.
I haven't seen it for a long time.
No loss!

 

[Casey]

Sounds a bit like polysulphide. I use it underwater under the copper tingle over the bung and on the inspection plate in the centreboard or anywhere else which I will need to take apart. It still sticks like mad but not as fiercely as Sikaflex.

 

[Hoilung]

I have been advised to use Polysulphide (by the surveyor, and various chums and aquaintances) on the skin fittings on Hoi Lung, and also in those areas where there has been a bit of shrinkage whilst she has been out of the water. I should add that my personal experience is very limited, but I should know more in a month or so once we launch!

 

[Adge]

Can I use Sikaflex on damp/wet wood

 

[Peterduck]

Your description sounds a lot like Stockhom Tar with, perhaps, a touch of gelatine. By itself, I think that Stockholm Tar would have soaked into the wood after that length of time, but with a gelling additive I think that it would be a plausible and very durable sealant.
Peter.

 

[Mirelle]

Just to add one more theory: I removed a mushroom vent from Mirelle's after deck which had been there for 48 years and the white lead paste that it had been bedded in was still good. Not, of course, light brown or translucent, but it does pick up colour from surroundings eg verdigris from bronze makes it go light green, and so on.

 

[rjp]

Thanks for the suggestions and comments folks. I suppose it still remains a bit of a mystery but Stockholm Tar or polysulphide sound like the most likely answers. I must admit, whatever it was, I was very impressed at how well it had lasted and even more impressed with how easy it was to remove the fitting. I have a supply of Sikaflex all ready to use, but am still hesitating to commit to it, knowing how difficult it is to remove again. As I'm talking below the waterline I'm also hesitant to experiment.

John

 

[youngwrinkley]

Try Plumbers Mate - by Evode. Stays permanently flexible - avaible from all good DIY shops - and cheap! Every boat should have some

 

[rjp]

I had thought of that, but discounted on the basis of it being non-marine and therefore slightly questionable below the waterline. (I have no problem with trying non-marine things above the waterline.) But your post suggests that you have some experience of it, so could you tell me what you used it for, how long it has lasted etc. Anyone else used Plumbers Mate?

John

 

[youngwrinkley]

Plumbers Mate is great for everything from Blakes seacocks, to transducers, even bedding my lead keel to the deadwood - also a bit around the keelbolts - but with a few turns of caulking coton for good measure. On the keel, I had to tighten the bolts slightly each year until it stopped squeezing out!

An old salt at Brightlingsea introduced me to it around 20 years ago - been using it ever since. It's best feature is that it never goes hard and you can always break the joint.

Above the waterling I've used it for bedding down quadrant in the cockpit floor, bedding deck hardware and bedding windows. BUT lately (2years) I have started using screwfix E-Strip weatherstrip (D12530) for windows and deck fittings - big advantage is that it doesn't squeeze out!

I have no connection with the manufacturers!

 

[rjp]

Very many thanks for that information. It sounds really good, so I will probably try it. Thanks also for the window sealant information. I've rebedded mine with teak coloured 'butyl' window sealant from the local builders merchant. So far so good, but it hasn't been anywhere near salt water yet!

John